Okay, so I'm using a Nikon D5200 and an iOptron SmartEQ pro. I've used this combination successfully with SGP 2.3 to do imaging. Ever since I upgraded to 2.4 it seems that the mount and the camera conflict.
If I take a single shot or activate live view with the mount disconnected, the camera behaves normally. When I activate the mount, there is about a 15 second lag on live view, and downloading a single frame suddenly takes 30s or longer. About half the time, SGP will just crash outright with both the camera and mount connected, if the mount is in motion.
The mount is connected via a usb-serial adapter, the camera is straight USB.
I've also tried connecting the camera to Digicamcontrol with the mount connected, and it goes to live view and captures fine with DCC.
Don't know if it will help, but I've taken a short .mov file that shows what happens when I connect the mount. I can't attach it to this post, but let me know if you want to see it and I'll send it to you.